<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <canvas id="hb" width="400" height="400"></canvas>
  <script>
    var h1=document.querySelector("#hb")//获取画布
    var ctx=h1.getContext("2d")//获取画笔
    ctx.beginPath()
    ctx.arc(200,200,100,0,(Math.PI/180)*360)
    ctx.closePath()
    ctx.stroke()
    ctx.beginPath()
    ctx.arc(160,145,10,0,(Math.PI/180)*360)
    ctx.closePath()
    ctx.stroke()
    ctx.beginPath()
    ctx.arc(240,145,10,0,(Math.PI/180)*360)
    ctx.closePath()
    ctx.stroke()
    ctx.beginPath()
    ctx.arc(200,200,50,0,(Math.PI/180)*180)
    ctx.stroke()
    ctx.closePath()
    
    // ctx.arc(145,145,5,0,(Math.PI/180)*90)
    // ctx.stroke()
  </script>
</body>
</html>